For the existing in-cell touch panel, a tested flexible printed circuit (FPC) pre-bonding method is usually adopted to perform voltage testing.
Reference is made to FIG. 1. An in-cell touch panel 10 includes an array substrate 102. The array substrate 102 includes a display region 101, and multiple signal lines are formed on the array substrate 102. The signal line includes a transient lead 103 formed at the periphery of the display region and pins connected correspondingly with the transient lead 103. Reference is further made to FIG. 2, which is an enlarged view of the pins of FIG. 1. The pins include touch pins 104 and display pins 105, which are respectively connected with corresponding transient leads 103. The transient lead 103 includes a metal electrode, an insulating layer formed on the metal electrode, and a second wire formed on the insulating layer by depositing material such as indium tin oxide (ITO). The second wire is electrically connected with the transient lead 103 via a second through-hole 106 in the insulating layer. The second through-hole 106 is located above the metal electrode. The touch pins 104 and the display pins 105 are arranged at intervals on the same level. Before the array substrate is crimped to the flexible printed circuit (FPC), there is a need to use a test board to perform the voltage testing on all touch pins 104, determine whether there is a problem of short circuit, open circuit, weak connection and the like in the touch pins according to a detected capacitance value, and perform the subsequent processes after the test is passed. Since the touch pins 104 are spaced by the display pins 105, each of the detection portions of the test board needs to correspond to each of the individual touch pins 104 one-to-one. Moreover, when the detection portion of the test board is pressed onto the touch pins 104, the detection portion should not contact with the display pins 105 around the touch pins 104, therefore, the alignment of the detection portion and the touch pin 104 is very difficult and a window for testing is very small.
Generally, in order to make the testing become simpler, the touch pins 104 are usually widened in the design stage. However, because the size of the touch pins 104 is too small, even if they are widened, only a width in an order of several hundreds of microns can be achieved in consideration of size limitations such as the gap between the pin and the border of the screen. Specifically, the width of the touch pin 104 is very small, which is typically about 80 μm; and the gap between the touch pins 104 is also small, which is typically about 40 μm. Moreover, due to the existence of load capacitance, the display pin 105 has a different voltage resistance from the touch pin 104. Therefore, when testing the FPC, it is unable to test multiple adjacent touch pins at the same time. Moreover, there is a need to strictly align with each touch pin 104 while pre-bonding the FPC, which results in a difficult operation and a low testing accuracy. Besides, the existing testing fixture is cumbersome and is unable to be used widely.